Delta Movement Issues, one axis moves double

Evenin’ lads,

So I’ve got a shoddy delta I picked up a couple years back (EZT3D T1)
and stopped using because it just always had problems, mainly stemming from the control board.

I just recently revived it using an SKR Mini E3
(I configured Marlin on it for a delta)
and it works well aside from one issue

  • the motor plugged into the X axis will randomly decide to just start moving twice the distance the other two motors move, and it doesn’t go back to normal until I power cycle it.

Any idea what could be causing this?
I’ve got a fan directly on the heatsinks for the drivers so I doubt they’re overheating, and this isn’t my first rodeo with upgrades and firmware config either… But I’m stumped.

:formated to be better readable (Daniel)

can you provide the config?
Is there any banding so the stepper looses steps?

Sure thing, config and config_adv are in a zip here:

Steppers don’t appear to be losing steps, although I haven’t been able to print with it yet so I’m not too sure about banding.

I am unsure with the microstepping.

But in general the config should be ok…

What would you suggest setting the microstepping to? I figured that the TMC2209’s could handle up to 256 microsteps, so 32 shouldn’t be an issue.

have you tried to rotate the motors

x driver -> x motor
y driver -> y motor
z driver -> z motor


x driver -> z motor
y driver -> x motor
z driver -> y motor

to check if the issue moves?
Then you have the answer if it is the motor or the stepper dirver

I don’t know what kind of black magic voodoo you just did but after swapping the motors (and endstops, which I totally didn’t forget the first time) now everything moves properly. It needs a new extruder motor idler arm before it can actually print anything, but motionwise it seems to be smooth as butter.

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Unfortunately, it seems the voodoo magic wore out.
The issue seems to be triggered by the motors moving large distances above a certain speed - I can raise and lower the effector in its full range just fine, but if I have the machine home itself all the way from Z=0, halfway to 2/3 of the way up the motor plugged into the X driver makes a short grinding noise and starts moving double.

I took a short video to illustrate this: